


Des-Purr-Ate Measures

by alfisha



Series: Tomarry Oneshots [3]
Category: Harry Potter - J. K. Rowling
Genre: Animal Transformation, Cat Puns, Cat Tom Riddle, Cat!Tom, Crack, Fluff and Crack, Harry Potter & Tom Riddle Attend Hogwarts Together, Harry Potter & Tom Riddle Grow Up Together, Kinda, M/M, Sane Tom Riddle, Shh, Slytherin Harry Potter, Tom Riddle is a Little Shit, harry calls tom Tomcat, harry is Tired™, i dont know how im gonna describe this, it's not mentioned tho, neville saw something he didnt want to, omg they were dormmates, they're just dormmates, this fic is so bizarre
Language: English
Status: Completed
Published: 2020-04-14
Updated: 2020-04-22
Packaged: 2021-03-02 01:28:41
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,440
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23646961
Author URL: https://archiveofourown.org/users/alfisha/pseuds/alfisha
Summary: In which Tom comes up with another plan for achieving immortality, and Harry is the best exasperated boyfriend.
Relationships: Harry Potter/Tom Riddle
Series: Tomarry Oneshots [3]
Series URL: https://archiveofourown.org/series/1708141
Comments: 34
Kudos: 689





	1. Chapter 1

**Author's Note:**

> inspired by a conversation i had with duplicity on her discord server about tom as a cat taking the whole 'cats have nine lives' thing too literally. i changed it up a bit but might make a second work with cat harry :))
> 
> also she named this work so blame amanda for the terrible (awesome) pun.

Harry stopped dead as soon as he stepped foot in the Slytherin dorms.

He blinked once. Twice. Three times.

Just as he was about to call out into the common room to see whose idiot cat had ripped up his bed, he got a face full of fur. 

"Yeuck-" he spluttered, as the claws digging into his shoulders forced the weight of this small, black kitten into his face, forcing him to almost swallow an obscene amount of cat hair. "Get off me, you little-" 

Then, he stopped struggling.

Because this cat was looking at him in that irritated, condescending way that only two people in the world could pull off, and he was fairly sure this cat wasn't McGonagall's breed... He shut the dorm door behind him slowly, casting several silencing spells, and finally managed to shove the scrawny animal unceremoniously from his body to his bed.

He stared at the cat, and the cat stared defiantly back.

Naturally, he burst out laughing.

"T-Tom?!" he managed to squeak out between gasps, and the cat hissed at him reproachfully.

Definitely Tom.

"I can't believe you. Are you an animagus? Why didn't you tell me? Also, seriously? A kitten? That's hilarious. And surprisingly fitting, I suppose. But really, why wouldn't you tell me something that important?" he asked, but the cat just continued to stare, its feline features somehow managing to morph into a scowl reminiscent of Tom's humanoid face. Harry stopped laughing because _oh yeah, cats can't fucking talk._

"Oh... right. No speech. Gotcha. Okay, time for a good old game of yes and no. Are you an animagus?" The cat continued to stare, because of course, even as a literal fucking animal, Tom Riddle would never do anything as plebeian as a nod or shake of his head. Harry knocked his glasses lower down his nose to pinch the bridge of it, sighing exasperatedly. 

"Blink once for yes, twice for no."

Tom blinked twice.

At least Harry got the small pleasure of knowing how frustrating it must be for someone as expressive as Tom to be confined to such simplistic answers, especially since he couldn't even speak said answers. He pushed the thought away quickly as the response settled in. So, he wasn't an animagus. Harry frowned as he readjusted his glasses. 

"How did you-" he started to ask, but was cut off by an indignant hiss. "Oh, shit, yeah. Sorry. Erm... was this an accident?"

Two blinks. A hesitation. Another blink.

"I wish we knew morse code, this is getting confusing. Wait, knowing you, you probably _do_ know morse code. Nerd. Okay, so, I'm gonna use my big brain here-" Tom let out the feline equivalent of a snort, which sounded a bit like a minuscule and totally non-offensive sneeze, but Harry glared anyway. "and I'm gonna guess that you willingly transformed yourself into a cat - for whatever reason - but that you were an idiot and somehow screwed up and can't morph back. Blink once if I'm correct, twice for not."

Tomcat clearly didn't want to admit to being an idiot, or that he screwed up, as Harry so eloquently put it, but blinked once all the same. Not without a soft growl from the back of his throat, however, but Harry blissfully ignored it and smirked triumphantly at his small victory. He had to force himself to school his features to be more composed, thinking fast. 

"Do you know how to get out of this?" he asked before he committed to coming up with a potentially unnecessary plan. 

One blink. Of course. The control freak wouldn't do anything without having a solution for all possible outcomes to the situation first. Harry sighed again. 

"Great. We'll need the library, I'm guessing?" One blink. "Okay. It's late, and if I get caught out of bed again I'm dead, so it'll have to wait until tomorrow."

Tom let out a frustrated huff in response, and Harry grinned impishly at him. "You're lucky today's a Friday." he reminded, taking extra care to make sure he sounded extremely irritating. 

Tom yowled.

Harry's grin faded as his eyes landed yet again on his bed, at the torn sheets and ripped pillows and feather-strewn duvet. He narrowed his eyes at Tomcat, who suddenly looked very smug. That wouldn't do at all. 

Harry set his bed right with a flick of his wand, and laughed as the tiny kitten turned from triumphant to defeated. He didn't get into bed; instead, Harry made his way to Tom's bunk, snapping the curtains shut and erecting numerous muffling, privacy and sticking wards on the material. Once done, he turned back to Tom, who looked taken aback - at least, Harry thought he did, it was hard to read a cat's expressions if they didn't consist of annoyance or happiness. So far, he'd only had experience with one.

"I'll say you're sick and don't want to be disturbed. I put a muffling and privacy on there because it'd be weird if they didn't hear coughs or something when there weren't any silencing spells, and a strong sticking charm so they don't peek inside."

Tom leapt off the bed and pawed at the green curtains of his own bunk, yowling frustratedly.

Harry felt his face burn, and looked away awkwardly. "I thought that, now you had the chance without anyone knowing it was you, you might wanna sleep with your boyfriend. But I'll uh... I'll undo the sticking charm if you don't want to. It was dumb, really, don't worry about it..." he mumbled, undoing the required charm on Tom's curtains and moving away to get ready to go to sleep.

The cat froze, looking between Harry's bed and his own, and then to the door.

Harry came out of the bathroom a few moments later, clothes changed and teeth cleaned, and flopped onto his bed before releasing the privacy wards on the dormitory door. He turned the lights out, knowing the others wouldn't be back until at least 2am, and removed his glasses. Tom was still stuck between the two beds, weighing up his options...

"Night, Tom."

And Tom crumbled.

He darted over to Harry's cot, and leapt onto the mattress before curling up under Harry's arm. Harry smiled softly to himself as Tom purred contentedly - though he'd never admit he'd done it - and reached out to thread his fingers through Tom's midnight black fur slowly, coaxing the both of them into relaxation. Tomcat didn't object, only purred louder, and so Harry kept petting until finally, he fell asleep.

**~**

Harry woke to the candles shining, Grindylows screeching, and a claw to the face.

"Agh- You bastard!" he seethed at the proud-looking black kitten that had scampered away to sit at the end of his bed. Tom's ear cocked towards their still-sleeping dorm mates pointedly and Harry scowled. He said nothing, however, only swung his legs over the edge of the bed - effectively knocking Tom over with his feet in the process - and put on his glasses. Around twenty minutes later, and Harry was sitting at a table in the library with a cat under his robes. He threw a strained smile at a suspiciously watching Madam Pince and averted his gaze quickly, opening a thick tome on animal transfiguration.

Which apparently warranted a bite to the ribs.

"What the fuck is your problem?" he hissed at Tom, trying not to move his mouth and make the librarian think he was talking to himself. Once Madam Pince had left her desk and turned away to go yell at snogging teenagers, Harry placed a heavy disillusionment charm on the dumb cat as he shot out from the confinement of Harry's uniform. Tom gave him a very affronted look, and Harry couldn't help the smirk gracing his lips.

"Why'd you bite me, you git?" he asked with a raised eyebrow.

Tom jumped down from where he sat on the table. From the floor, he looked pointedly up at Harry, who glanced around to make sure Pince was preoccupied before getting up to follow him. Tomcat led him over to the Herbology section, which really didn't make much sense to Harry, but he followed along anyway. He couldn't hold back his scepticism when Tom pawed at a book titled _Murderous Mushrooms and How To Befriend Them: Volume Seven_ that looked like it had sat there, untouched, for decades. Harry's scattered brain wondered vaguely how well the other six volumes had sold, and why there were so many murderous mushrooms in the world.

"Lemme guess: you ate the _special_ type of mushroom, got high as fuck, and spontaneously turned into a cat." he said, expression deadpan.

Tom hissed insistently, and pawed the book some more.

"I'm not picking up that book." he said, eyeing the grimy cover in thinly veiled disgust.

Tom's eyes seemed to pierce through him, judging...

He picked up the book.

To his surprise, out fell a piece of parchment, conveniently addressed to him in Tom's elegant handwriting. He looked at the cat, who nudged at the fallen note with his tiny nose.

"You're mental." he declared, and scooped up the note to read it. The cat mewled in what Harry assumed was disagreement to his words, but Harry paid him no mind as he scanned the writing in his hands.

' _Harry James Potter,_

_If you are reading this, I am a cat.'_

Harry snorted, and Tomcat hissed.

' _I did this with the hopes of achieving the gain of the fabled nine lives that cats are said to have. It turns out that my research was... flawed, in ways, and I am now both unable to return to my original self independently, and have no access to those nine lives. This is one of many notes I had written to you depending on the outcome of my experiment, and I shall collect and destroy the others when I return._

_I'd very much appreciate it if you could use the Finite Incantatum spell on me, so that I may once again morph back into my human body. Don't screw this up._

_-Tom Marvolo Riddle_ '

Harry sighed heavily, and looked down at the cat in disdain.

"You're such an idiot." he said tiredly, and Tomcat narrowed his eyes impatiently. Sighing again, Harry took out his wand and cast the spell.

A naked Tom Riddle materialised in the middle of the aisle of bookshelves.

Harry let out a surprised squeak and looked away quickly, very aware of how hot his face felt.

"Why the fuck did you do it _now_?" Tom hissed angrily, trying unsuccessfully to cover himself up.

"You didn't say you'd be naked!" Harry protested, and he didn't have to look to know that Tom was glaring at him.

"It's kind of common sense, Harry-"

"Are you really gonna try talking about common sense after trying to gain immortality from a _cat body_? You're not in a position to judge stupidity after pulling off a stunt like that."

"It was a reasonable theory."

"No, it was a bullshit theory! Everyone knows cats don't _actually_ have nine lives, Tom! It's a myth!"

"Muggles think magic is a myth," Tom pointed out. "Now, if you don't mind, I'd rather not be having a naked argument in the library."

Harry huffed and shed his outer robe, leaving himself in the standard school shirt and slacks - it was a weekend but he preferred the school uniform to his ill-fitting muggle clothes - and held them out to Tom without looking at him. When he'd finished pulling on Harry's slightly too-small clothes, Harry glanced at him and smirked at his dishevelled appearance.

"What're you smiling at?" Tom asked bitterly, cheeks still flushed an enticing red from the earlier predicament. 

"Your hair's all messed up." Harry stated, and Tom rolled his eyes. Amused, Harry leaned forward and planted a small kiss on one of his disgruntled boyfriend's coloured cheeks, and smiled as he pulled away and took his hand. "Come on, before someone sees Perfect Tom Riddle looking like he's been living like an animal- oh wait..." he trailed off purposefully, and laughed as Tom continued to glare at him. "You love me." he sing-songed playfully.

Tom's expression softened - Harry still found himself amazed at how it was _him_ who caused that to happen - and he grasped Harry's hand more firmly.

"I do, you brat."

They walked out of the library, leaving behind a very confused and equally traumatised Neville Longbottom in the Herbology section.

Because Neville, who generally naturally blended into the bookshelves, had witnessed everything.

He made a mental note to ask the matron for an Obliviate.

**~**


	2. The Unfortunate Witness - Neville Longbottom

**Summary for the Chapter:**

> Neville is having a very bad day.

**Notes for the Chapter:**

> neville's pov of the day! this probably isn't gonna be very long, or very well-written, it's purely for the lols. poor neville, he saw something he didn't want to, and now the author is torturing him by describing his day. fun!
> 
> hope you enjoy :))

Neville was having a Bad Day.

One Bad Day in a series of Bad Days, to be honest.

First, he managed to explode three cauldrons consecutively in his Double Potions class, before then tipping over a fourth and releasing what seemed to be an  _ alive  _ thick paste into the classroom with the students. He earned himself a week’s detention, which he knew he deserved, but it still sucked ass.

Next was the mess that was Charms class. They were revisiting the summoning charm - this time with heavier objects, and Neville had  _ known  _ then that this wasn’t going to end well - and the majority of the class did wonderfully, summoning and banishing their items with ease.

Key word being  _ majority _ .

Neville, on the other hand, sent five vases flying out of the window, two teapots smashing into the wall, and one accidental chair crashing into the ceiling.

Neville figured he was right to believe that so far, this qualified as a Bad Day.

He was quite relieved to return to his dormitory in the Gryffindor Tower at the end of a long and tiring Bad Day filled with unfortunate scenarios and devastating accidents. He fell asleep with the hope that tomorrow would be better.

He should have known that that would not be the case.

The morning started off well enough, he awoke earlier than the others, and dressed without tripping over, so he deemed that a success. Then he remembered that he had a whole day of nothing to do, and that he should go and find the Herbology book that Professor Sprout had recommended. 

He didn’t walk in on anyone in the bathroom, which was always a plus.

He didn’t fall down the Tower stairs, which was a huge accomplishment, what with his two left feet.

He didn’t even run into Filch on his early trek down to the library, which was honestly a massive relief.

Overall, this morning was feeling pretty great.

The sunlight filtering in through the windows in the halls allowed him to see the thousands of small specs of dust drifting in the air, and he stared in awe at the fluid motions that to him looked like dancing. But he wouldn’t really know, dancing had never come naturally to him. Nothing had.

He got to the library soon enough, and wandered over to the Herbology section. The shelves were dusty and unused, the books mostly mouldy and with fraying spines, their covers peeling and ripped; but that didn’t matter to him. This section of the library was like another home. As he scanned through the books, he heard a peculiar sound.

A hiss.

That couldn’t be right. Animals weren’t allowed in the library! He shrugged, assuming it was McGonagall scaring off some first-years or something, and settled down in a shadowy alcove amongst the shelves as he pulled down the one he wanted.

But there was another noise. This one sounded more human… a voice!

He peeked around the corner of shelves, and sitting a few metres away, was a black kitten.

A talking cat? What the-

No, he got it wrong. There was Harry Potter, staring down at the cat with a look of exasperation. The voice had belonged to him. Of course. Neville was about to go over and say hello, as he’d always been friendly with Harry - he was one of the only Slytherins that left him alone, and encouraged others to do so, too.

But then he realised that Harry didn’t even have a pet cat.

And he didn’t have any interest in Herbology.

And he was looking at the cat like… like…

Like it could understand him.

"Lemme guess: you ate the  _ special  _ type of mushroom, got high as fuck, and spontaneously turned into a cat." he said, expression deadpan. The cat hissed and scratched a book on a shelf.

“I am not picking up that book.” he told the cat, and the cat was- the cat was  _ glaring  _ at him?

Neville was quite confused now, and whenever he was confused and shocked at the same time, his body tended to freeze up, and all he could do was stare at the… confrontation?

_ What the fuck… _

Harry picked up the book.

Neville couldn’t see the title from where he sat, but he could see that it was just as grubby and dirty as any of the others, so he could understand Harry’s reluctance to touch it. What he didn’t understand was why on earth he was taking orders from a cat.

A slip of parchment fell from the book’s pages, and Harry took a moment to inform the cat: “You’re mental.” before swiping up the note and reading it.

A second later, he snorted. The cat hissed again. 

After around a minute, Harry sighed heavily and stared at the cat with an expression that Neville could only describe as Tired. He’d seen his Gran give him the same look when he’d done something particularly stupid.

“You’re such an idiot,” he told the cat, though Neville was starting to wonder if it even  _ was  _ a cat. Harry sighed again and did a spell that Neville couldn’t hear, and then Neville knew that the cat was definitely  _ not a cat at all. _

Because suddenly, in the cat’s place, was a very dishevelled, and a very  _ naked  _ Tom Riddle.

Neville couldn’t even function enough to cover his eyes.

Harry squeaked at the sight, and Neville found a slither of comfort in the fact that he wasn’t the only one that was incredibly flustered here.

“Why the fuck did you do it  _ now _ ?” Tom asked angrily, trying to cover himself with his hands. It wasn’t working too well.

“You didn’t say you’d be naked!” Harry whisper-shouted, still looking the other direction. Tom was wearing an expression that looked as though he wanted to murder Harry, though Neville knew he wouldn’t have to be concerned about that. If it were someone else there in Harry’s place,  _ then  _ he’d worry. But this was Harry, and Neville knew that Tom wouldn’t hurt him.

“It’s kind of common sense, Harry-”

"Are you really gonna try talking about common sense after trying to gain immortality from a cat body? You're not in a position to judge stupidity after pulling off a stunt like that."

"It was a reasonable theory."

"No, it was a bullshit theory! Everyone knows cats don't actually have nine lives, Tom! It's a myth!"

"Muggles think magic is a myth," Tom pointed out. "Now, if you don't mind, I'd rather not be having a naked argument in the library.”

Neville would rather that, too, as he was becoming both incredibly confused and incredibly embarrassed at having listened in for so long.

He watched as Harry handed over his outer school robe - why was he wearing uniform? - and as Tom pulled the too-small clothes over himself. Harry turned back to look at him then, and smirked at what he saw. 

“What’re you smiling at?” Tom asked with an annoyed edge to his voice that would’ve made anyone else hesitate, but Harry just smiled some more.

“Your hair’s all messed up.” he stated, and Tom rolled his eyes.

Neville struggled to stay quiet as Harry leaned over and planted a small kiss on one of Tom’s blushing cheeks before pulling away and taking one of his hands. “Come on, before someone sees Perfect Tom Riddle looking like he’s been living like an animal- oh wait…” he trailed off, and Neville blinked in confusion as Harry laughed at Tom’s scowl.

He felt as though he was definitely missing something.

“You love me,” Harry said in a chirpy tone, and Neville held his breath in shock. Riddle didn’t love anyone…

But Tom’s expression was softening, and he tightened his grip on Harry’s hand. 

“I do, you brat.” 

They walked out of the library, leaving behind a very confused and equally traumatised Neville Longbottom in the Herbology section. 

Because Neville, who generally blended into the bookshelves, had witnessed everything. 

He made a mental note to ask the matron for an Obliviate.

**Notes for the Chapter:**

> "What do you mean they 'don't just hand out Obliviates to anyone'? I am in desperate need!"

**Author's Note:**

> hey, you should check out my other oneshots.  
> it would make me very happy.
> 
> only if you want 🥺👉🏻👈🏻  
> also follow my tumblr. https://alfiisha.tumblr.com/


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